Seedless Vascular Plants

Lycopodiophyta: Lycophytes Pteridophyta: Ferns Lycophytes = club mosses also include the spike mosses and Quillworts Lycopodiophyta: Lycophytes Pteridophyta: Ferns 4 orders of true ferns + Psilotales: Whisk ferns Equisetales: Horsetails

Characteristics of the Seedless Vascular Plants Vascular tissues (protostele, siphenostele, few have eustele) Well developed cuticle Lignin & cellulose in secondary wall Protected Sporangia In most, sporangia are aggregated into strobili Have dominant sporophytes Require water for fertilization

Leaves in the Seedless V. P. Microphylls mostly associated with protostelic stems, no leaf gaps, common lycophytes Megaphylls: associated with stems that have siphonostele or eustele, have leaf gaps evolved as fusion of branch systems Enations: scale-like outgrowth devoid of vascular tissues Microphylls: evolved from enations, with a single vein Megaphylls: evolved as modified branches, have branched veins

Phylum Lycopodiophyta: Lycophytes Mostly tropical Consist of 3 living orders each with a single family All living genera are herbs with microphylls Consist of 3 living orders each with a single family (Club mosses, spike mosses, & quillworts)

Club Mosses: F. Lycopodiaceae Example: The genus Lycopodium * All living genera, except two, are classified in this family Seven genera are represented in U.S. & Canada but most species are tropical & epiphytes Roots & stems are protostelic Homosporous, sporangia are in axils of fertile leaves (sporophylls) In Lycopodium, sporophylls are grouped into strobili * Sporophyte consists of branching rhizomes.

Lycopodiella inundata Lycopodium obscurum Lycopodiella inundata Locopods Modern members of the Lycopodophyta are relatively small plants, many with creeping rhizomes bearing upright branches. Lycopodium obscurum is a common club moss of northern forests Lycopodiella inundata grows in some bogs in our area. It can survive extended immersion in shallow water Spores are produced in sporangia, tiny sac-like organs born at the base of leaves near the tip of the stems The sporangium bearing leaves are often packed into a dense, cone-like structure (Strobilus)

Lycopodium digitatum

An Epiphytic Club Moss

Spike Mosses: F. Selaginellaceae One genus Sellaginella (700 species)* Tropical, many found in moist habitats, few are desert plants Sporophylls arranged in strobili (Heterosporous)* Has micro- & megasporophylls Microsporangia are carried on upper portion of the strobilus Has microsporophylls (fertile leaves carry microsporangia) Has megasporophylls (carry megasporangia)

Selaginella denticulata

Sporangia (Selaginella underwoodii) http://www.wnmu.edu/academic/nspages2/gilaflora/selaginella_underwoodii.html

Selaginella arbuscula http://zipcodezoo.com/photographers/Charles%20H.%20Lamoureux.asp

Selaginella involvens Selaginella apoda Selaginella Selaginella involvens Two species of Selaginella grow wild in New York State, S. apoda and S. rupestris S. involvens is a native of Eastern Asia; this specimen is cultivated in the Brooklyn Botanic Garden. Broad arrow that appears on click is link back to group slide

Selaginella spp

Resurrection Plant (Selaginella lepidophylla) Desert plant: Found in TX, NM, and Mexico

Quillworts: F. Isoetaceae One genus Isoetes* They are aquatic, or found in seasonally flooded habitats Plants look like grasses, with underground stem (corm) All leaves are potential sporophylls Heterosporous, lower leaves are megasporophylls, upper microsporophylls

Quillworts: Microsporangia & Microspores

Quillworts: Megasporangia & Megaspores

Quillworts: Habitat

Pteridophyta: Psilotales Whisk Ferns Consist of one family & two genera They are the simplest vascular plants Represent an early lineage related to living ferns

Wisk Fern: Genus Psilotum* Tropical and subtropical in distribution (S. States) Protostelic Lacks roots, has rhizomes & rhizoids Leaves are represented by enations Dominated sporophyte, homosporous Gametophyte is heterotrophic, either symbiotic or parasitic on soil fungi Xylem consists of thick tracheids,

Psilotum Sporophyte Sporophyte

Psilotum nudum

Psilotum nudum Sporangia

Wisk Fern: Genus Tmesipteris Sporangia http://www.science.siu.edu/landplants/Psilophyta/psilophyta.html Confined to South Pacific Grows as an epiphyte on tree ferns & other plants Has microphylls

Pteridophyta: Equisetales Horsetails Represented by 1 genus, Equisetum (horsetails)* It is the oldest survivor of plants Widespread in moist habitats and edge of forests Has jointed stem (nodes) & rough texture Has microphylls Homosporous, sporangia are clustered into strobili Recognized by its jointed stem (nodes) & rough texture Stems arise from underground rhizomes (eustele) Some species have fertile and sterile stems Gametophyte is green and free living (size of a pinhead)

Strobilus Branches Leaves Equisetum arvense

Equisetum is the only living genus in the Equisetophyta The stems of horsetails are constructed somewhat like those of bamboo, with internodes of regular length separated by nodes each of which bears a whorl of tiny leaves In those species that form branches, the branches also occur in whorls at the nodes E. arvense produces short-lived, non-photosynthetic fertile shoots in the spring followed by these branched green shoots that live all summer The underground rhizome lives for many years Equisetum arvense

Equisetum hyemale E. hyemale rarely produces branches As with other species of Equisetum, the sporangia are born in strobili at the tips of the stem Broad arrow that appears on click is link back to group slide

Phylum Pteridophyta: True ferns: The largest group of living seedless vascular plants (11,000 spp) They are found in a variety of habitats 3/4 are tropical 1/3 of tropical ferns grows as epiphytes 1/4 inhabits temperate regions & desert Ferns are second only to flowering plants (235,000 spp)

Polystichum acrostichoides Sporangia are produced on the underside of the terminal portion of the leaf in P. acrostichoides

Dryopteris carthusiana (mature sporangia) Mature fern sporangia are barely distinguishable to the unaided eye Broad arrow that appears on click is link back to fern life cycle Dryopteris carthusiana (mature sporangia)

Fern: Morphology Most ferns of temperate region produce annual leaves from subterranean rhizomes Leaves are megaphylls (fronds), constitute major part of the sporophyte Ferns are the only seedless vascular plants with megaphylls Most ferns are homosporous, water ferns are heterosporous

Fern Morphology Frond: compound leaf of ferns Pinnae (leaflet) Rachis (extension of petiole Petiole: leaf stalk

Fern Spores Sorus

Fern Gametophyte Archegonia Antheridia Rhizoid

Text Pg. 567 Fern Life Cycle Click on the broad arrow at upper right to go to photos of fern sporophytes and sporangia The broad arrow that appears at lower right after a click on this slide is a link to the next section of the presentation Although there are differences in the details, the fern life cycle shares many characteristics with the life cycles of other seedless vascular plants The large photosynthetic and usually long-lived sporophyte is the plant we usually recognize (contrast with mosses and liverworts) Spores are produced by meiosis in a sporangium Spores are usually dispersed by the wind Spores germinate to grow into a small, inconspicuous gametophyte which may be photosynthetic (in ferns) or may be subterranean and dependent on association with soil fungi for nutrition (in some species of other groups) Gametes (eggs and sperm) are produced in Gametangia (archegonia and antheridia) produced on the gametophyte Sperm are flagellated, motile, and require the presence of liquid water in which to swim to the archegonia, enter them, and fuse with the egg The zygote divides to form an embryo which develops into a functional young sporophyte while still attached to the gametophyte

Diversity of Ferns

Pteridium aquilinum (Common Brake)

Athyrium filix-femina var. angustum (Lady Fern)

Dryopteris intermedia (Common Wood Fern)

Matteuccia struthiopteris (Ostrich Fern)

Onoclea sensibilis (Sensitive Fern)

Water Ferns Include two orders: Marsileales & Salviniales Constitute the only living heterosporous ferns Marsiliales – Marsilea Salviniales – Salvinia & Azolla

Marsilea spp. Resembles a four-leaf clover. Grow on mud or submerged with floating leaves

Marsilea spp Sporocarp (at base of plants)

Salvinia: Aquatic Habitat Small plant, float on surface of water http://extension.entm.purdue.edu/CAPS/pestInfo/giantSalvinia.htm

Aquatic Fern: Salvinia http://agspsrv95.agric.wa.gov.au/dps/version02/01_plantview.asp?page=7&contentID=57& Has undivided leaves Plants float freely

Salvinia: Leaf & Hairs Hairs protect leaf from getting wet & allow them to remain above water

Aquatic fern: Azolla Weed of the Rice paddies Has bilobed leaves Leaves have pouches that harbor the nitrogen-fixing bacteria (Anabaeana) Azolla spp.

Cyanobacteria such as Nostoc & Anabaena possess a heterocyst where nitrogen fixation takes place Azolla caroliniana

Azolla caroliniana at Rice Creek Pond (red) Azolla caroliniana at Rice Creek Pond (red). The other plants are duckweeds.

Azolla caroliniana on Mud